You live and learn, but too much information can be a bad thing as demonstrated in this warm, witty and very shrewdly observed romance. The unlikely pairing of Julia Louis-Dreyfus and James Gandolfini (in one of his last roles) is intoxicatingly fizzy, but they're old enough to know that falling head over heels can leave lasting bruises.

Albert (Gandolfini) is the more laidback of the two despite having gone through a messy divorce, but the story is seen through the doubting eyes of Eva (Louis-Dreyfus), also divorced and raising her daughter Ellen (Tracey Fairway) alone. She meets Albert while Ellen is preparing to leave for college and, emotionally speaking, she's a little ragged around the edges but otherwise keeps a bright and sunny outlook.

That begins to change as Albert becomes a more serious prospect. Writer/director Nicole Holofcener usually takes a loose, sometimes unruly approach to storytelling (in films like Jennifer Aniston starrer Friends with Money), but what she does so brilliantly this time is trace the line from sparkling self-confidence to crippling insecurity in a very subtly curving arc.

At the party where Eva and Albert first clap eyes on each other, she is careless enough to bemoan the lack of good-looking men. He makes a joke of it and a few dates later she finds herself caring too much, thoroughly disarmed by his good humour. Frankly, it could go either way when she turns up for brunch all dressed up and he answers the door in sweatpants that flap open at the crotch.

Mostly, their shared sense of humour helps them get over the bumps in the early stages of their relationship, but the balance begins to tip when Eva makes a new friend, Marianna. It's a quietly hysterical turn by Catherine Keener - a poet swathed in silks who wafts around like Mother Earth. She is a classic Californian New Age hippy except for an un-karmic habit of badmouthing her ex - a fat slob who was terrible in bed and had no ambition.

Inevitably, Eva compares this loser to the man she was beginning to think was Mr Right and sees worrying parallels. A seed of doubt grows and it affects the way Eva behaves towards Albert, pointing out his foibles to him and becoming more aloof. Naturally, the more she fusses, the more irritable he gets and the more worried she becomes that they aren't suited.

It's an absurd cycle, comic as it is tragic, although a couple of plot turns threaten to send it too far into sitcom territory. Toni Collette has a more down-to-earth philosophy as Eva's married pal Sarah who is good for a few laughs and keeps Eva from going completely crazy. But her voice is drowned out by Marianna who Eva looks up to as an evolved being, inflating her own insecurities.

One of Holofcener's strengths is her ability to portray female friendships with all their underlying politics, as well as delivering some great salty banter. Still, Eva's relationship with Albert is the anchoring force in a truly heartfelt romance and there's a genuine sense of peril as she rocks the boat, threatening to drive away the best thing that's ever have happened to her - enough that your own heart will be in your mouth.